Procedure to copy a certificate pack out of a starkit for openssl to read

proc tkjabber::get_cafile {} {
    global env
    set path [file join $::tkchat_dir certs.pem]
    if {![file exists $path]} { return {} }
    if {[lindex [file system $path] 0] ne "native"} {
        set new {}
        foreach var {TEMP TMP TMPDIR} {
            if {[info exists env($var)] \
                    && [file isdirectory $env($var)] \
                    && [file writable $env($var)]} then {
                set new [file join $env($var) tkchat.pem]
                break
            }
        }
        if {$new eq {}} {
            if {[file isdirectory /tmp] && [file writable /tmp]} {
                set new [file join /tmp tkchat.pem]
            } else {
                log::log error "cannot find a tempfile location"
                return {}
            }
        }
        log::log info "copying certificate collection to $new"
        file copy -force $path $new
        return $new
    }
    return $path
}